1. Field of Invention
The present invention relates to driver chips for LED devices and, more particularly, to an apparatus in which a plurality of driver chips, a power supply and a plurality of LED chips are integrated on an integrated isolative substrate for easy manufacturing, preventing surges, protection against lightning strikes, reducing electromagnetic interferences, and improving heat radiation to prevent thermal effect.
2. Related Prior Art
More and more attention has been paid to the protection of the environment. Accordingly, there is an on-going trend to improve energy efficiency. The LED industry is a promising one because LED devices are energy efficient, efficient, fast to react, long in life, mercury-free and environmentally friendly.
Regarding the development of a heat radiation substrate of a high-voltage driver IC, the high-luminance LED chips and a package are included in a module and a driver IC is included in another module in a conventional design. In the conventional design, the driver IC must be modularized, and the cost is therefore high and the heat radiation is therefore poor.
Furthermore, an LED device converts only about 20% of electricity into light but converts the other portion of the electricity into heat. In most cases, the heat is transferred to a substrate from at least one LED chip and then transferred to a system-class circuit board from the substrate. Finally, the heat is released into the environment from the system-class circuit board.
However, an LED device is often expected to provide high luminance, last for a long period of time and operate stably. Many LED-based street lamps are used currently. A requirement for an LED-based street lamp is that its luminous decay must be lower than 20% for at least thirty thousand hours of operation. Most of the current LED-based street lamps however stop to operate before thirty thousand hours of operation. One third of the reasons why they fail are attributed to unstable driver IC. The primary reason for an unstable driver IC is failure to radiate heat from the driver IC fast enough.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.